Australia 1999 Centenary100 Dollars - Elizabeth II 4th portrait; Sovereign - unlisted UNC type 50,000 ?

Regarding Numista catalogue listing for a Proof coin: https://en.numista.com/catalogue/pieces17356.html, I have stumbled across a dealer in Australia selling an UNC (not Proof) version on eBay:http://www.ebay.co.uk/itm/321640804817?&orig_cvip=true.

The coin, COA and case are quite reasonably pictured and that suggests a previously unlisted UNC version.
The pictured COA gives a mintage of 50,000 for it.

However, the listing description refers to a actual mintage of 977 and a "catalogue value" of $475 (could be AUD).  That compares with $750 (USD) in Krause for the Proof version.  I haven't asked where the quoted 977 "actual mintage" figure came from.

The proof version is KM#474 in totally different packaging and numbered COAs with mintage 7,500. I can't find the UNC version in Krause.

The (proof only) Numista catalog entry may well need updating ...

Anyone know more?

If you find more information regarding this or if you wish to add that to the catalog you can send me a PM and I will fix it for you.